Materials Performance

MAR 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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56 MARCH 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 3 When the water contains Cl – , it can penetrate the corrosion product and di- rectly attack the steel substrate, shown in Equation (9): Fe × H 2 O + Cl – → FeClOH ad – + H + + e (9) During this corrosion process, Cl – itself is not consumed and is available to corrode more steel, as shown in Equations (10) and (11): 9 FeClOH ad – → FeClOH + e (10) FeClOH + H + → Fe 2+ + Cl – + H 2 O (11) Conclusions Based on this analysis, it may be con- cluded that corrosion of the newly installed domestic heating system was caused by the following factors: • The high-salt make-up water con- tains a large amount of corrosive SO 4 2– and Cl – ions and a relatively low pH value. • Neith er dea eration nor soft ening were used for the make-up water, and the water had a high oxygen concen- tration and hardness. • The protective rust layer in the steel pipe inner surfaces had not formed effectively during such a short period of operation time. Recommendations To reduce corrosion and prolong the service life of the newly installed family heating system, the following recommen- dations should be considered: • Replace the high-salt water with low- salt water as the make-up water. • As it is difficult to deaerate the make- up water, maintain the delivery pipe full of water, and evacuate the air in the pipe as much as possible. • Add a corrosion inhibitor to th e delivery water to increase the water's pH value or other wise reduce the steel dissolution rate. References 1 Pravila tekhnicheskoi ekspluatatsii teplovykh energoustanovok (St. Petersburg Russian Federation: Dean Press, Ltd., 2003). 2 C. Cao, Principle of Electrochemistry on Corro- sion, 2nd ed. (Beijing, China: Chemical In- dustry Press, 2004), p. 76. 3 L. Wang, et al., "Corrosion Analysis of a Steel Drinking Water Pipe in an Indoor Environ- ment," MP 51, 9 (2012): pp. 61-65. 4 G.S. Vasyliev, et al., "A Study of the Anti- Corrosion Properties of Carbonate Deposits to Protect Low-Carbon Steel from the Action of Tap Water," Russian J. Applied Chemistry 87 (2014): pp. 450-455. 5 Y.V. Balaban-Irmenin, N.G. Fokina, "Corro- sion Inhibitors for Small-Scale Heat-Supply Systems," Protection of Metals 44 (2008): pp. 698-703. 6 Y. V. B a l a b a n - Ir m e n i n , A . M . R u b a s h o v, N.G. Fokina, "The Effect of Phosphonates on the Corrosion of Carbon Steel in Heat-Supply Water," Protection of Metals 42 (2006): pp. 133-136. 7 E.P. Rozanova, et al., "Microorganisms in Heat Supply Systems and Internal Corrosion of Steel Pipelines," Microbiology 72 (2003): pp. 179-186. 8 C.X. Jin, et al., "Corrosion Analysis of the Steel Structure Surrounding a Coal-Fired Boiler Heating Plant," MP 54, 1 (2015): pp. 72-74. 9 C. Leygraf, T. Graedel, Atmospheric Corrosion (New York, NY: John Wiley & Sons, Inc., 2000): pp. 287-290. 10 M. Yamashita, et al., "The Long Term Growth of the Protective Rust Layer Formed on Weathering Steel by Atmospheric Corrosion During a Quarter of a Century," Corros. Sci. 36 (1994): pp. 283-299. 11 T. Misawa, K. Hashimoto, S. Shimodaira, "The Mechanism of Formation of Iron Oxide and Oxyhydroxides in Aqueous Solutions at Room Temperature," Corros. Sci . 14 (1974): pp. 131-149. 12 M. Stratmann, K. Bohnenkamp, H. Engell, "An Electrochemical Study of Phase-Transi- tion in Rust Layers," Corros. Sci. 23 (1983): pp. 969-985. 13 U. Evans, C. Taylor, "Mechanism of Atmo- spheric Rusting," Corros. Sci. 12 (1972): pp. 227-246. 14 J. Wang, et al., "The Corrosion Mechanisms of Carbon Steel and Weathering Steel in SO 2 Polluted Atmospheres," Materials Chemistry and Physics 47 (1997): pp. 1-8. ZHANJUN GUO is a teacher at the Institute of Environmental & Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, Henan, 450000, China. He teaches and conducts research relating to environmental and municipal engineering. ZHILIANG CHEN is an administrator at the Yangzhou Research Academy of Energy a n d M a t e r i a l , C h i n e s e A c a d e m y o f Sciences, Yangzhou, Jiangsu, 225000, China. He conducts research relating to environmental sciences and engineering. AUTHORS WANTED NACE is looking for industry experts to write and edit NACE published books and compilations. Contact Jonnie Fuller +1 281-228-6496 jonnie.fuller@nace.org MATERIALS SELECTION & DESIGN

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